The purpose of this project is to take empirically supported, clinic-based treatment programs for child conduct disorders and evaluate their short- and long-term efficacy as low-cost, school- based, early intervention programs for preventing the development of ODD and CD. 21 Head Start centers will be randomly assigned to receive the universal classroom intervention (CR) or to be control schools (CONTROL). An indicated sample of children (top 1/3 on aggressive behavior) will also be identified. All indicated children will receive detailed home assessments and a subset of this indicated sample from CR schools will be randomly assigned to receive the parent intervention (PT). Thus, there are three conditions, CR, CR + PT, and CONTROL. The CR intervention will consist of teacher training in classroom management strategies plus training in the delivery of the Dinosaur social skills and problem-solving curriculum. The PT intervention will focus on strengthening parenting skills that promote social and academic competence, reduce conduct problems, and foster parents' school involvement. Both the universal and the indicated interventions will be offered during the Head Start year and the indicated PT intervention will continue through kindergarten. This school-based intervention for Head Start children includes carefully integrated interventions that maximize consistency and follow-through in he two most important environments of the young child's life, the home and the school. The videotape format for both the classroom and the parent intervention increases the consistency, fidelity and transportability of the program implementation, and makes it easier and less costly to implement and maintain in real-world settings. Outcome will be measured by comparing the three intervention conditions in terms of conduct problems, child social and academic skills, parent competencies and school involvement, teacher classroom management skills and classroom environment. A cost benefit analysis will be conducted for the two levels of treatment. Multiple assessment methods will be used including independent home and classroom observations as well as teacher and parent reports. Follow-up assessments will be conducted at the end of kindergarten and grade one.